Adequate cooling for electronic equipment, in particular, equipment having a large number of printed wire/circuit boards (PWBs/PCBs) or “circuit cards”, is critical for preventing damage and extending component service life. The large amount of heat generated by the components arranged on these cards often necessitates separate conductive cooling systems in order to control the operating temperature of the equipment. These cooling systems may comprise, for example, heat exchangers embodied as heat-conducting chassis or frames. These chassis may be air or liquid-cooled, or may simply comprise a large thermal capacity. Cards are traditionally held on their ends within slots formed on opposing “cold walls” of the chassis (see FIG. 1A).
Cards inserted into these cold wall slots are typically clamped in place along their opposing edges via expanding “wedge locks” or “card retainers” (see FIG. 1B). Conventional card retainers suffer from several significant drawbacks. For example, they do not exert uniform pressure along the length of the card edge(s) as a result of their multi-piece construction. This multi-piece construction is also not ideal for efficient heat conduction, and thus, heat sinking from the card primarily results only from conduction on a side opposite the card retainer and its contact with the cold wall. Moreover, these card retainers do not allow for easy extraction of the cards, or the retainers themselves, because they often do not fully contract back to their non-expanded height, even when properly unlocked. Finally, the active cooling in many of these systems comes from coolant channels formed in the chassis walls, which can be arranged at a relatively large distance from the card. This distance can lead to significant thermal rise between the fluid in the channels and the card edges.
Alternative systems and methods are desired for providing both improved card retention and cooling.